1. Field of the Invention
The present invention relates to light-emitting diode constructions.
2. Description of the Prior Art
Related to the problem of distorted video projections are the fundamental problems inherent in of pixel and light-emitting diode construction, particularly in the construction of large area flat panel displays. Light-emitting diodes (or "LEDs") are semiconductor devices designed to convert an incoming flow of electric energy into an outgoing flow of electromagnetic radiation having wavelengths of between about 550 nanometers (green color) to about 1300 nanometers (infrared). Known LEDs are limited to emitting a specific color such that a diode might emit, for example, a red color and a neighboring diode might emit, again for example, a green color.
Diodes today are formed from materials including gallium, indium, aluminum, arsenic, and phosphorus. The individual diode is built up upon a gallium arsenide single-crystal substrate. As is known, an n-type layer of vapor-deposited gallium arsenide phosphate is formed over the single-crystal substrate, followed thereafter by a p-type layer, also formed by vapor-deposition. Ohmic contacts are formed on both sides of the LED.
A major difficulty of known LEDs is a result of the fact that very little of the light energy produced by the diode can, in fact, escape the diode and, as a consequence, only a few percent of the consumed electrical input results in externally observable light. Compounding this problem is the extraction of the radiation into an optical fiber. This is so because the optical fiber has a relatively narrow light acceptance angle of between about 10 and 15 percent. To improve light transmission between the LED and an optical fiber, the construction of LEDs is modified such that a well is formed in one side of the substrate and one end of the optical fiber is positioned in the well. Other modifications are made to the LED to improve light transmission into the optical fiber, such as the deposition of additional layers of material upon the substrate. However, the loss of light energy between the LED and the output end of the optical fiber is still of considerable consequence and presents a great limitation to the versatility of known LEDs.
An additional difficulty of known LEDs is the redundancy and multiplicity of transistors driving each of the pixel pads which comprise the individual LEDs. Because each known LED requires its own power source, there is extensive and expensive use of the transistors.
In general, the present invention provides improved displays through fiber construction, a holographic interface, the use of plastic LED light emitters, semi-conductor manufacturing tools, and the incorporation of automated final assembly.